Method and apparatus for releasing a perforation and sealing tool from a well bore

ABSTRACT

A method and an apparatus are provided for releasing a fluid tight seal formed about a well bore perforation by a perforating and sealing tool. A pressure differential across the sealing means urges the fluid tight seal into engagement with a well casing adjacent a perforation. To release this seal and remove the perforating and sealing tool from the well bore, the pressure differential acting on the seal is eliminated by equalizing the pressures acting on the two faces of the seal. The equalization may be effected by bleeding high pressure fluid through the seal from the high pressure side to the low pressure side to a central aperture formed therethrough during the formation perforation step. Alternatively, the high pressure fluid may be carried to the central aperture of the seal through the perforating and sealing tool itself, which high pressure fluid may be metered into the tool through plug orifices. Each plug orifice may be opened by the explosive charge of the perforating tool. This charge would knock off the plug of the plug orifice and establish fluid communication between the high pressure fluid and the interior of the tool. Alternatively, the plug portion of the plug orifice may consist of material such as magnesium which will dissolve in surrounding liquid after a predetermined period of time so as to establish fluid communication between annular fluids about the tool and the interior of the tool.

United States Patent Briggs, Jr.

[54] METHOD AND APPARATUS FOR RELEASING A PERFORATION AND SEALING TOOL FROM A WELL BORE Inventor: George E. Briggs, Jr., Houston, Tex.

Halliburton Company, Okla.

Feb. 20, 1970 [73] Assignee: Ducan,

Filed:

Appl. No.:

US. Cl. ..l7S/4.52, 166/ 100, 166/301 Int. Cl ..E2lb 43/116, E21c l9/00 Field of Search ..l75/4.52; 166/301, 100

[56] References Cited UNITED STATES PATENTS 9/1958 Chivens et a1. 166/100 X 12/1960 Brieger et a1. ..l75/4.52 X l/ 1967 Brieger et al. ..175/4.52 2/1967 Brieger ..175/4.52 X

Primary Examiner-David H. Brown Attorney-Bums, Doane, Benedict, Swecker and Mathis [57] ABSTRACT A method and an apparatus are provided for releasing a fluid tight seal formed about a well bore perforation by a perforating and sealing tool. A pressure differential across the sealing means urges the fluid tight seal into engagement with a well casing adjacent a perforation. To release this seal and remove the perforating and sealing tool from the well bore, the pressure differential acting on the seal is eliminated by equalizing the pressures acting on the two faces of the seal. The equalization may be effected by bleeding high pressure fluid through the seal from the high pressure side to the low pressure side to a central aperture formed therethrough during the formation. perforation step.

Alternatively, the high pressure fluid may be carried to the central aperture of the seal through the perforating and sealing tool itself, which high pressure fluid may be metered into the tool through plug orifices. Each plug orifice may be opened by the explosive charge of the perforating tool. This charge would knock off the plug of the plug orifice and establish fluid communication between the high pressure fluid and the interior of the tool. Alternatively, the plug portion of the plug orifice may consist of material such as magnesium which will dissolve in surrounding liquid after a predetermined period of time so as to establish fluid communication between annular fluids about the tool and the interior of the tool.

12 Claims, 7 Drawing Figures P'A'TENTEDsEP 5 m2 SHEEI 1 0F 2 mvnmon GEORGE E. BRIGGS, JR.

BY R s, 210m, Rmau swam Mm:

PATENTED SE? 5 I973 3.688.849

suwznrz [NV ENTOR BY mnx, bom Peanuts Mectu 6. M

.nronssvs GEORGE E. BRIGGS, JR.

METHOD AND APPARATUS FOR RELEASING A PERFORATION AND SEALING TOOL FROM A WELL BORE BACKGROUND OF THE INVENTION The present invention relates generally to the art of perforating and completing wells, and, more particularly to methods and apparatuses for assisting the removal of a perforating and sealing tool from a well bore after a perforating process has been completed.

Explosive perforator equipment and methods wherein a mass, such as a projectile, or a jet is fired into a formation to accomplish perforation are generally employed to establish communication between formation fluids and a tool disposed within a well bore traversing the formation. The producing zone defined by the perforation within the formation is often termed a perforation envelope as discussed in U.S. Pat. No. 3,305,018 issued to White et al. and assigned to the assignee of the present invention. It is desirable that such a perforation envelope should comprise a large, sub stantially unrestricted flow path for fluids entering the perforation envelope from the formation or for fluids passing from the wellbore into the formation in order that the perforation may have a maximized flow capacity with any given pressure differential applied thereacross.

Prior art explosive perforator apparatuses and methods have often produced results which are less than the desired results and the securing of perforation envelopes having the necessary flow properties has long been considered a problem. One of the primary causes for this problem appears to be that, although the existing perforating equipment produces satisfactory perforation envelope depths and volumes initially, the perforation envelope may subsequently become plugged with detritus from the crushed formation which plugging may progress to the extent that the perforation envelope may acquire a flow resistance thereacross greater than the naturally occurring flow resistance of the formation. Of course, this condition prevents the formation fluids from flowing from the formation to the well bore.

It is therefore desirable to clean the detritus from the perforation envelope immediately upon the formation thereof so as to insure a proper flow rate from the producing area into the well bore. It is also desirable to establish an isolated flow path from the formation to a conduit within the well bore which conduit may comprise: a low pressure chamber for drawing detritus from the perforation envelope, a formation fluid sampling tool or a production string. F urtherrnore, it is necessary to provide for the removal of the perforating and sealing tool after the completion of the related operations.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method and an apparatus for alleviating many of the problems encountered in perforating and completing well bores.

It is another object of the present invention to provide an apparatus and method for removing a conduit from a well bore which conduit is being held against a perforation site of the well bore by a differential pressure applied thereacross.

It is still another object of the present invention to provide a method and apparatus for reducing the blockage of a perforation envelope caused by formation detritus plugging the path differential by the perforation.

It is yet another object of the present invention to provide a backup apparatus and method for'releasing'a tool from a well bore casing, which too] is held by differential pressure, in the event that'a primary pressure equalizing system should fail.

It is a further object of the'present invention to provide a means for equalizing the'pressure across a perforating and sealing tool urged against the casing of a well bore by differentialpressure which apparatus and method are relatively uncomplicated. and inexpensive.

Other and further objects of the'invention will be obvious upon anzunderstanding of the illustrative embodiment about to be described, or willbe-indicated in the appended claims, and various advantages not referred to herein will occur to one-skilledin the art upon employment of the invention in practice.

The above-listed objects of the present invention are carried out by the provision of means for metering fluids from a high pressure side to a low pressure side of a sealing portion of a perforating tool urged against a perforation site by a differential pressure applied thereacross.

In one feature of the invention, the high pressure fluid is metered through the sealing means itself and directed toward an aperture formed therein for passing formation fluids therethrough. Thehigh pressure fluids so directed prevent formation detritus from plugging the apertures formed within the sealing means.

In another feature of the invention, plug orifices are mounted within a casing of the tool with the plug portion of the plug orifice being removable so as to establish fluid communication between an outer highthe following detailed description which may be best understood when taken in connection with the accompanying drawings in which:

FIG. 1 is an overall pictorial view of a tubular perforating and sealing tool disposed within a well bore;

FIG. 2 is a partial sectional view of a perforating and sealing portion of the tool shown in FIG. 1 taken along the longitudinal axis thereof;

FIG. 3 is a pictorialview of a sealing pad used to establish an isolated flow path from a formation fluid area into the tool shown in FIG. 1;

FIG. 4 is an enlarged axial partial sectional view of the perforating and sealing means shown in FIG. 2;

FIG. 5 is a partial sectional view of the apparatus shown in FIG. 4 taken along the line 5-5;

FIG. 6 is a pictorial view of a plug orifice which may be mounted within the tool shown in FIG. 2 and used to meter fluids through the tool casing upon removal of a plug portion thereof; and

FIG. 7 is a partial sectional view of the plug orifice shown in FIG. 6 taken along the longitudinal axis thereof.

Referring now to the drawings in which like numerals are used to indicate like parts throughout the various views thereof, FIG. 1 shows a well bore drilled within a formation 12 and having a casing liner 14.

A perforating and sealing tool, indicated generally as 16, may be supported within the bore 10 by means of a cable (not shown) attached to a cable head 18 formed at the top of the tool 16. The portion of the tool 16 immediately below and adjacent to the cable head 18 may comprise a formation fluid sampling chamber 20. The lower end of the formation fluid sampling chamber 20, in turn, may be connected with an explosive activated valve 22 for closing the inlet to the fluid sampling chamber before removal of, the tool from the well bore 10.

A perforating and sealing section 24 is attached immediately adjacent and below the valve portion 22 of the overall tool 16. Perforation site sealing pads 26 are mounted on the outer casing of the perforating and sealing portion 24. A perforating gun (shown in FIGS. 2, 4 and 5) is disposed within the section 24 behind each of the sealing pads 26. Decentralizing drag springs indicated as 28 and shown reversed more detail in FIGS. 2 and 5, are disposed on the opposite side of the tool from the pads to urge the sealing pads toward the bore casing adjacent a site to be perforated. The function of the drag springs 28 and their location will be discussed in more detail later in the specification. The lowermost portion of the tool may comprise a residue chamber 30 for retaining the fluids which are not assimilated by the formation fluid sampling chamber 20. It should be understood that, the residue chamber 30 and the formation fluid sampler chamber 20 may be reversed in position within the tool 16 so that the sampler chamber occupies the lowermost portion thereof and the residue chamber is disposed at the upper end thereof adjacent the cable head 18.

A high pressure hydrostatic fluid occupies the well bore annular space about the tool. The magnitude of the pressure of the hydrostatic fluid within the annular space about the tool is substantially higher than the low pressure formation fluids within the producing area 12 and it is this pressure differential which is utilized to secure an effective seal immediately upon perforating the formation. It is also this pressure differential which must be equalized in order to release the seal provided by the pads 26 which hold the entire tool 16 against a perforation site.

Referring now to FIG. 2, the perforation and sealing section 24 of the overall tool 16 is shown in partial longitudinal cross section as having a drag spring means 28 bowed outwardly from two mounting screws 34 embedded within the casing 36, i.e., body means, of the tool. Referring briefly to FIG. 5, it can be seen that two such drag springs 28 may be mounted, spaced circumferentially 120 away from the mounting of the sealing pad 26. The drag spring operates as a decentralizer to urge the pad 26 into proximity with an area of the well bore casing to be perforated. The drag springs operate as a guide to insure that the tool moves longitudinally within the bore along the axis of the bore hole 10. The drag springs, similarly, insure that the sealing pad 26 seats flush and parallel against the casing liner 14 before the actuation of the perforating device. Upon firing the perforating device, the drag springs prevent the tool from spinning as might result if the springs were not present. Another advantage of the drag spring is to insure that the drag wear on the sealing pads 26 is uniform as the tool is inserted within the bore hole.

A formation perforating gun indicated generally as 38 is disposed within the tool and is properly aligned transverse the axis of the tool by positioning a frusto conical, axially extending projection 40 into a correspondingly shaped recess 42 formed in the interior wall 44 of the tool. A barrel end 46 of the gun is aligned with a mounting stud 48 which impingingly secures the sealing pad 26 to the outer surface of the tool casing 36. Electrical lines 50 maybe included for detonating the perforating gun 38.

Referring to FIG. 3, a sealing pad 26 of the present invention is shown with the mounting stud- 48 inserted therethrough. It will be noted that the head of the mounting stud is formed in the shape of a hex nut to facilitate the threaded engagement of the mounting stud within the casing 36 of the tool. The sealing pad 26 should be elastomeric and may comprise a material such as synthetic or natural rubber.

A high pressure bleed orifice 52 may be formed through the body of the sealing pad 26 to extend from the area adjacent the mounting stud 48 to an outer lip 54 thereof. It will be noted, that the general configuration of the sealing pad 26 is such as to conform to the outer surface of a conduit such as perforating and sealing tool. When the perforating gun 38 disposed behind the sealing pad 26 is detonated, a projectile or shaped charge gasses rupture the head of the mounting stud 48 and penetrate deeply into the formation adjacent the sealing pad 26. The aforementioned high pressure hydrostatic fluid surrounding the outside of the tool then flexes the lip 54 of the pad 26 toward the perforation site due to the substantial pressure differential between the low pressure formation fluids and the high pressure hydrostatic fluid. After the initial deflection movement of the pad 26, the entire tool is urged against the perforation site by the differential pressure. At this point, detritus and various and sundry debris within a perforation envelope formed by the gun 38 flows from the low pressure formation into a lower pressure maintained within the tool itself.

The bleed orifice 52 communicates the high pressure hydrostatic fluid with the lower pressure within the aperture of the mounting stud so that hydrostatic fluid is metered into the casing side of the sealing pad 26. The gradual pressure buildup on the casing side of the pad operates as an automatic delayed release mechanism whereby, by sizing the orifice 52, the low pressure fluids within the formation may pass into the lower pressure tool for a determined period of time until the orifice 52 has metered enough hydrostatic fluid into the casing side of the seal to equalize the pressure on that side of the seal with the tool side of the seal so as to release the seal pad 26 from the perforation site. This is therefore accomplished without the necessity for separate actuation from above the well bore.

As mentioned in the background discussion, it is desirable to keep the passageway leading from the perforated envelope into the tool clear of sand buildups. The orifice 52 then serves a double purpose by directing a high pressure stream of hydrostatic fluid laterally against the opening formed within the mounting stud 48 by the perforating gun as well as equalizing the pres sure on both sides of the sealing pad after a predetermined period of time. This second function of clearing the aperture formed within the stud 48 is of considerable significance in that it prevents the aperture from becoming so restricted by bridging sand as to present a greater resistance than the natural resistance within the formation which greater resistance would prevent the flow-of formation fluids into the tool.

Referring now to FIG. 4, the perforating gun 38 and the sealing pad 26 shown in FIG. 2 are shown in enlarged cross sectional view. The gun 38 is shown to contain a shaped charge 56 which is housed within an inner metallic container 58 and to be covered by an outer nonmetallic substance 60. The barrel end 46 of the gun 38 is shown to be properly aligned with an internal axial bore 62 formed within the mounting stud 48. External threads 64 are formed on the terminal end of the mounting stud 48 for engagement within internal threads 66 formed within the tool casing wall 36.

The sealing pad 26 may be provided with a rigid metallic annular disc 68 embedded therein to provide a rigid base upon which the mounting stud 48 may act so as to impinge the sealing pad 26 between the mounting stud 48 and the outer surface of the casing wall 36.

Alignment pins 70 may be mounted within the sealing pad 26 to extend generally normally therefrom to fit within cylindrical recesses 72 formed within the casing wall 36. The recesses 72 are arranged with respect to the geometry of the alignment pins 70 to insure that the sealing pad 26 is disposed generally coaxial to the barrel 46 of the perforating gun 38.

FIG. 5 shows the perforating gun 38 and sealing pad 26 of FIG. 4 taken along FIG. 5 and additionally shows the arrangement of the drag springs 28 disposed 120 from each other and from the mounting stud 48 about the circumferential periphery of the casing wall 36. A washer-like seal member may be disposed within an annular groove 74 formed as a stepped up portion of the bore defined by the internal threading 66 provided within the wall casing 36. The seal 73 prevents the high pressure hydrostatic annular fluids surrounding the tool from seeping behind the seal and along the outer surface of the mounting stud 48 into the low pressure interior of the tool defined by the casing 36.

While the function of the drag springs 28 has been described in detail in the foregoing paragraphs, it should, of course, be understood that the drag springs are not necessary for practicing the present invention. For, it is believed that by freely lowering the tool within the bore with no decentralizing members, that the pressure differential between the formation fluids and the hydrostatic fluids is sufficient in itself to move the sealing pad and tool into pressure engagement with the perforation site. This is a surprising discovery in that the general feeling heretofore has been that the perforating blast of the shaped charge 56 had a tendency to recoil the seal and tool away from the perforation site.

As can be seen from FIGS. 3, 4 and 5, the annular portion 76 surrounding the mounting stud 48 is formed with an approximately 45 chamfer to insure that, upon detonating the perforating gun 38, the seal is not shredded nor torn by the blast resulting therefrom. Such a shredding or tearing may result in the ultimate destruction of the seal when it is acted upon by the substantial pressure differential applied thereacross.

Additionally, the 45 chamfer insures that, if the seal course, understood that, after the shaped charge 56 is detonated within the perforating gun 38, the entire casing and barrel connected therewith is likewise blasted away from the mounting stud and all that remains is a through passage extending axially through the mounting stud into the perforation envelope which passageway is automatically sealed from annular fluids by the sealing pad 26. The low pressure formation fluids may then flow from the formation into the lower pressure maintained within the casing 36 of the overall tool 16.

Referring now to FIG. 6, an alternative embodiment of a delayed equalizing orifice is shown to comprise a plug orifice 80. Referring briefly back to FIG. 2, it can be seen that the threads 82 formed at one end of the plug orifice are mountingly engaged within internal threads 84 formed within the casing 36 of the tool. A plug portion 86 of the plug orifice 80 extends radially toward the center of the tool adjacent the perforating gun 38. The head 88 of the orifice plug is formed with recesses 88 into which a wrench-like tool may be inserted for threadingly mounting the plug orifice 80 into the aperture defined by the internal threadings 84 formed within the casing 36.

In operation, the blasting of the perforating gun 38 causes the plug portion 86 of the plug orifice 80 to be knocked off so as to expose a metering orifice 90 extending axially through the remaining portion of the orifice plug 80. The axial orifice 90 is sized so as to meter high pressure annular hydrostatic fluids surrounding the tool into the low pressure area within the tool which fluids then pass through the fluid passageway defined by the axial bore 62 of the mounting stud 48 so as to equalize the pressures on both sides of the sealing pad which equalization releases the holding force on the pad and permits the retrieval of the tool from the well bore 10. Therefore, the release may be effected without separate actuation from above the well bore.

FIG. 7 shows the preferred construction of the overall orifice plug 80 in partial longitudinal sectional view. The plug portion 86 comprises a generally solid cylindrical projection having integral therewith and extending axially therefrom a threaded cylindrical portion 88. A necked-down section 92 connects the two cylindrical portions 88 and 86 which necked-down portion 92 presents a substantially smaller cross sectional area than the cross sectional area of the sections 88 and 86 so that a shearing force applied to the portion 86 would result in a failure at the necked-down portion 92.

The metering orifice 90 extends from the head portion 89 of the overall plug orifice 80 axially through section 88 thereof and through the necked-down portion 92 partially into the knockoff portion 86. It will be apparent that, when a shearing force causes a failure in section 92, the metering orifice 90 will then extend axially entirely through the remaining portion of the device. External threads 94 formed on the cylindrical portion 88 are engaged with internal threads 96 formed: within an annular mounting stud 98. External threads 82 are formed on the mounting stud 98 and, as previously described, threadedly engage within threading 84 defining the mounting aperture within the tool casing 36.

The mounting stud 98 is formed with a radially extending collar portion 100 which impinges a resilient fluid seal 102 between a radial surface 104 of the collar 100 and in the outer surface of the casing 36. Of course, an annular groove not shown) may be formed around the threading 84 defining the aperture into which the overall orifice plug 80 is to be mounted which annular groove may be utilized to maintain the seal 102 so that the head 89 of the overall orifice plug may be flush with the outer surface of the casing 36 when properly mounted therein.

The mounting stud 98 for the plug orifice 80 may also be formed with an internal shoulder 106 which may cooperate with an external shoulder 108 formed on the threaded portion 88 of the knockoff plug 86 to retain an O-ring seal 110 between the two shoulders. The two seals 102 and 110 insure that the high pressure hydrostatic fluids outside the casing 36 cannot seep into the low pressure space maintained within the easing 36.

An alternative embodiment of the orifice plug 80 as operationally shown in FIG. 2 as a knockoff plug, is one in which the portion 86 of the overall orifice plug 80 consists of a material, such as magnesium, which dissolves in the presence of salt water. In such an embodiment, if an included pressure differential equalizing slide valve (not shown) fails to properly function or becomes clogged and if the perforating gun 38 fails to knock off the plug portion 86 of the overall plug orifice, the plug would then dissolve in the presence of salt water after a period of approximately 12 hours. This alternative embodiment then provides a fail-safe feature in which a delayed equalization of the differential pressures acting across the sealing pad 26 is insured.

It can thus be seen that a simple method and apparatus have been provided for sealing an isolated flow path from a perforation envelope, blasted within fluid producing formation, into a perforating and sealing tool. It can also be seen, that a relatively inexpensive means and method have been provided for releasing the sealing engagement of the tool against the perforation site which engagement is caused by a pressure differential applied across the sealing pad.

The method and apparatus embodied within the plug orifice feature of the present invention permits high pressure fluid to be metered to the low pressure side of the sealing pad so as to effect the release of the seal after a predetermined period of time which is a function of the orifice size and the hydrostatic pressure of the annular high pressure fluids.

The embodiment of the present invention including a bleed orifice formed within the sealing pad, itself, and extending from a lip thereof to the central aperture formed therein serves a dual purpose. Such a bleed valve provides a delayed equalization of pressures between both sides of the sealing pad while simultaneously directing high pressure fluid against the aperture connecting the perforation envelope in the formation with the interior of the tool so as to keep the aperture clear of detritus materials from the perforation envelope.

A fail-safe feature of the plug orifice embodiment of the present invention is provided in that the knockoff plug of the plug orifice piece may comprise a dissolvable material which will dissolve within a certain period of time of exposure to the fluids surrounding the plug, Thus, if a primary pressure equalizing slide valve fails to function, or if the perforating gun does not knock off the plug of the plug orifice piece, the orifice will still be permitted to communicate the interior of the tool with the fluids surrounding the outer casing of the tool when the plug dissolves so as to expose the inner axial end of the plug orifice to the space defined by the casing of the tool.

While drag springs have been shown as a part of the perforating and sealing tool, these devices are not necessary for satisfactory operation thereof. This feature is due to the discovery that, when the perforating gun is detonated, the recoil thereof does not drive the sealing pad away from the casing wall and the perforation site but, instead, the pressure difference across the sealing member drives the outer lips into immediate sealing engagement with the perforation site which action of the sealing pad then pulls the tool itself with it so as to eliminate the need for a decentralizing drag spring.

The structure of the orifice plug as shown in FIG. 7 provides a composite wherein the mounting stud may be reused with a new insert after a previously used insert has been destroyed by the plug portion thereof being knocked off or dissolved. This feature provides an economical advantage in using the present invention.

The 45 chamfer formed on the low pressure side of the seal in the area annularly adjacent the mounting stud, insures that the perforating blast does not shred or tear the sealing pad. Also, the chamfer insures that the aperture formed through the seal by the action of the perforating gun will not be easily misaligned with the axis of the peroration envelope within the formation. The alignment pins extending generally normally from the general axis of the sealing pad also assist in coaxially aligning the sealing pad with the axis of the perforating gun barrel.

It should be understood that the arrangement of sections within the overall tool shown in FIG. 1 of the drawings may be rearranged so that the sample chamber and the residue chamber could be reversed.

While what has been shown in the detailed description is a preferred embodiment of the invention, it is, of course, understood that various modifications and changes may be made therein without departing from the invention and therefore it is intended to cover in the appended claims all such modifications and changes as fall within the true spirit and scope of the invention.

What I claim is:

l. A well formation perforating and sealing tool comprising:

a. body means including interior conduit means;

b. web means mounted on said body means, said web means including outer lip means;

c. said web means being operable to move into sealing cooperation with a perforation site, defined within a formation surrounding a well bore;

d. formation perforating means carried by said body means and disposed adjacent said web means;

e. said formation perforating means having means for directing explosive energy into said formation surrounding said well bore to form a perforation in said formation and to establish a flow path means and disposed adjacent said web means; e. said formation perforating means having means for directing explosive energy into said formation surrounding said well bore to form a perforation in said formation and to establish a flow path between fluid within said formation and said interior conduit means of said body means;

between fluid within said formation and said interif. said flow path being substantially isolated from a Conduit means of Said body means; hi h ressure well zone exterior of said bod f. said flow path being substantially isolated from a min]; y

high pressure well zone exterior of said body theimprovement comprising the steps of:

means; and detonating said formation perforating means to g. bleed orificcei) means communicating with said web establish said flow path between fluid within said means an eing responsive to establishing said formation and said flow path to meter fluid from a high pressure side interior conduit means of said body means;

to a low pressure side of said web means such that maintaining said flow path substantially isolated a ressure differential o eratin thereacross is from s id hi r s r w z n eq alized after a predetefmined period of time, said boi iy me s? e u e e o e extenor of which period of time is a function of the cross seccausing bleed orifice means to communicate with tional area of said bleed orifice means and said Said eb means and to meter fluid from a high Pressure differentialpressure side to a low pressure side of said web An apparatus according to claim 1 wherein Said means responsive to establishing said flow path; bleed orifice means extends from said outer lip means d of said Web mea1 1S to commufficate with saifl flow p causing a pressure differential operating across d d P I E I p g f jl and tool as said bleed orifice means to be equalized after a escfl e C an P" predetermined period of time, which period of oflffce P g means salfl y mefans and time is a function of the cross sectional area of disposed generally ad acent said formation persaid bleed orifice means and said pressure forating means and operable to define said bleed f ti L orifice means; 7. A method according to claim 6 wherein said im- Said orifice Plug means P P to Provide? provement comprises maintaining said bleed orifice metermg flow path for llrectmgblgh fluld means operable to extend from said outer lip means of from a Zone f of sand P to Send low said web means to communicate with said flow path. Pressure slde of Sam web means m response to 8. A method according to claim 1 wherein said imdetonation of said formation perforating means movement comprises:

3. means from sealing cooperation with said perforameans and disposed generally adjacent Sald form?- tion site. 31:1; ggrrggiaetirrrilg anrilzans and operable to define said An apparatus accorqmg to claim. 3 wherem i causing said orifice plug means to provide a metering Onfic? plug means Comprlse? a mountmg stud E flow path for directing high pressure fluid from a' by said body means and an insert member carried by 40 Said mounting Stud; well zone exterlor or said tool to said low pressure side of said web means In response to detonation said insert member being formed with an orifice operable to define said bleed orifice means and exof Sald forinatlon Perforating means whgreby a tending from a first end thereon partially toward pressure dlfferennal .apphed across web the Second end thereof; means may be equalized and release said web said insert member being formed with a necked m from sealmg cooperatlon wlth sald perfora' down portion adjacent the second end of said orifice whereby said insert may be sheared at said Awenfomanon perforatmg and sealmg toolcom' necked down portion by explosive energy acting pnsmg: on the second end of said insert member such that body means; said orifice thereafter extends entirely through the web f ""P sand body means sald web remaining portion of said insert. mfians mcludmg ouPer hp means;

5. An apparatus according to claim 4 wherein the Q 531d web mens befng operable Y seal second end of said insert member comprises a material "l f p p with a peffofatlon slte, defined which is dissolvable in salt water 55 within a formation surrounding a well bore;

6. In a method of effecting well formation perforata formatlon P means Carried y 531d ing and sealing with a tool comprising, y means and dlsposed adjacent 531d web a. body means including interior conduit means; means;

b. web means mounted on said body means, said web Said formation Perforating means having means for means including outer lip means; directing explosive energy into said formation surc. said web means being operable to move into sealr g Said bore t0 form a Perforation in ing cooperation with a perforation site, defined Said fOI'maIiOH a to establish a fl P within a formation surrounding a well bore; and between fluid within said formation and an interior d. formation perforating means carried by said body portion of said body means; and

f. bleed orifice means communicating with said web means and operable to meter fluid from a high pressure side to a low pressure side of said web means, such that a pressure differential operating thereacross is equalized after a predetermined period of time, which period of time is a function of the cross sectional area of said bleed orifice means and said pressure differential;

g. said bleed orifice means extending from said outer lip means of said web means to communicate with said flow path.

10. A well formation perforating and sealing tool comprising:

a. body means;

b. web means mounted on said body means, said web means including outer lip means;

c. said web means being operable to move into sealing cooperation with a perforation site, defined within a formation surrounding a well bore;

d. a formation perforating means carried by said body means and disposed adjacent said web means;

c. said formation perforating means having means for directing explosive energy into said formation surrounding said well bore to form a perforation in said formation and to establish a flow path between fluid within said formation and an interior portion of said body means; and

f. bleed orifice means communicating with said web means and operable to meter fluid from a high pressure side to a low pressure side of said web means, such that a pressure differential operating thereacross is equalized after a predetermined period of time, which period of time is a function of the cross sectional area of said bleed orifice means and said pressure differential;

g. orifice plug means mounted in said body means and disposed generally adjacent said formation perforating means and operable to define said bleed orifice means;

h. said orifice plug means being operable to provide a metering flow,'path for directing high pressure fluid from a well zone exterior of said tool to said low pressure side of said web means in' response to detonation of said formation perforating means whereby a pressure differential applied across said web means may be equalized and release said web means from sealing cooperation with said perforation site;

. said orifice plug means comprises a mounting stud carried by said body means and an insert member carried by said mounting stud;

j. said insert member being formed with an orifice operable to define said bleed orifice means and extending from a first end thereon partially toward the second end thereof;

k. said insert member being formed with a necked down portion adjacent the second end of said orifice whereby said insert may be sheared at said necked down portion by explosive energy acting on the second end of said insert member such that said orifice thereafter extends entirely through the remaining portion of said insert.

11. An apparatus according to claim 10 wherein the second end of said insert member comprises a material which is dissolvable in salt water.

12. In a method of effecting well formation perforating and sealing with a tool comprising,

a. body means; b. web means mounted on said body means, said web means including outer lip means;

c. said web means being operable to move into sealing cooperation with a perforation site, defined within a formation surrounding a well bore; and

d. a formation perforating means carried by said body means and disposed adjacent said web means;

e. said formation perforating means having means for directing explosive energy into said formation surrounding said well bore to form a perforation in said formation and to establish a flow path between fluid within said formation and an interior portion of said body means;

the improvement comprising:

providing bleed orifice means operable to communicate with said web means and operable to meter fluid from a high pressure side to a low pressure side of said web mean;

causing a pressure differential operating across said bleed orifice means to be equalized after a predetermined period of time; which period of time is a function of the cross sectional area of said bleed orifice means and said pressure differential; and

maintaining said bleed orifice means operable to extend from said outer lip means of said web means to communicate with said flow path. 

1. A well formation perforating and sealing tool comprising: a. body means including interior conduit means; b. web means mounted on said body means, said web means including outer lip means; c. said web means being operable to move into sealing cooperation with a perforation site, defined within a formation surrounding a well bore; d. formation perforating means carried by said body means and disposed adjacent said web means; e. said formation perforating means having means for directing explosive energy into said formation surrounding said well bore to form a perforation in said formation and to establish a flow path between fluid within said formation and said interior conduit means of said body means; f. said flow path being substantially isolated from a high pressure well zone exterior of said body means; and g. bleed orifice means communicating with said web means and being responsive to establishing said flow path to meter fluid from a high pressure side to a low pressure side of said web means such that a pressure differential operating thereacross is equalized after a predetermined period of time, which period of time is a function of the cross sectional area of said bleed orifice means and said pressure differential.
 2. An apparatus according to claim 1 wherein said bleed orifice means extends from said outer lip means of said web means to communicate with said flow path.
 3. A formation perforating and sealing tool as described in claim 1 and further comprising: orifice plug means mounted in said body means and disposed generally adjacent said formation perforating means and operable to define said bleed orifice means; said orifice plug means being operable to provide a metering flow path for directing high pressure fluid from a well zone exterior of said tool to said low pressure side of said web means in response to detonation of said formation perforating means whereby a pressure differential applied across said web means may be equalized and release said web means from sealing cooperation with said perforation site.
 4. An apparatus according to claim 3 wherein said orifice plug means comprises a mounting stud carried by said body means and an insert member carried by said mounting stud; said insert member being formed with an orifice operable to define said bleed orifice means and extending from a first end thereon partially toward the second end thereof; said insert member being formed with a necked down portion adjacent the second end of said orifice whereby said insert may be sheared at said necked down portion by explosive energy acting on the second end of said insert member such that said orifice thereafter extends entirely through the remaining portion of said insert.
 5. An apparatus according to claim 4 wherein the second end of said insert member comprises a material which is dissolvable in salt water.
 6. In a method of effecting well formation perforating and sealing with a tool comprising, a. body means including interior conduit means; b. web means mounted on said body means, said web means including outer lip means; c. said web means being operable to move into sealing cooperation with a perforation site, defined within a formation surrounding a well bore; and d. formation perforating means carried by said body means and disposed adjacent said web means; e. said formation perforating means having means for directing explosive energy into said formatiOn surrounding said well bore to form a perforation in said formation and to establish a flow path between fluid within said formation and said interior conduit means of said body means; f. said flow path being substantially isolated from a high pressure well zone exterior of said body means; the improvement comprising the steps of: detonating said formation perforating means to establish said flow path between fluid within said formation and said interior conduit means of said body means; maintaining said flow path substantially isolated from said high pressure well zone exterior of said body means; causing bleed orifice means to communicate with said web means and to meter fluid from a high pressure side to a low pressure side of said web means responsive to establishing said flow path; and causing a pressure differential operating across said bleed orifice means to be equalized after a predetermined period of time, which period of time is a function of the cross sectional area of said bleed orifice means and said pressure differential.
 7. A method according to claim 6 wherein said improvement comprises maintaining said bleed orifice means operable to extend from said outer lip means of said web means to communicate with said flow path.
 8. A method according to claim 1 wherein said improvement comprises: providing orifice plug means mounted in said body means and disposed generally adjacent said formation perforating means and operable to define said bleed orifice means; causing said orifice plug means to provide a metering flow path for directing high pressure fluid from a well zone exterior or said tool to said low pressure side of said web means in response to detonation of said formation perforating means whereby a pressure differential applied across said web means may be equalized and release said web means from sealing cooperation with said perforation site.
 9. A well formation perforating and sealing tool comprising: a. body means; b. web means mounted on said body means, said web means including outer lip means; c. said web means being operable to move into sealing cooperation with a perforation site, defined within a formation surrounding a well bore; d. a formation perforating means carried by said body means and disposed adjacent said web means; e. said formation perforating means having means for directing explosive energy into said formation surrounding said well bore to form a perforation in said formation and to establish a flow path between fluid within said formation and an interior portion of said body means; and f. bleed orifice means communicating with said web means and operable to meter fluid from a high pressure side to a low pressure side of said web means, such that a pressure differential operating thereacross is equalized after a predetermined period of time, which period of time is a function of the cross sectional area of said bleed orifice means and said pressure differential; g. said bleed orifice means extending from said outer lip means of said web means to communicate with said flow path.
 10. A well formation perforating and sealing tool comprising: a. body means; b. web means mounted on said body means, said web means including outer lip means; c. said web means being operable to move into sealing cooperation with a perforation site, defined within a formation surrounding a well bore; d. a formation perforating means carried by said body means and disposed adjacent said web means; e. said formation perforating means having means for directing explosive energy into said formation surrounding said well bore to form a perforation in said formation and to establish a flow path between fluid within said formation and an interior portion of said body means; and f. bleed orifice means communicating with said web means and operable to meter fluid from a high pressure side to a low pressure side of said web means, such that A pressure differential operating thereacross is equalized after a predetermined period of time, which period of time is a function of the cross sectional area of said bleed orifice means and said pressure differential; g. orifice plug means mounted in said body means and disposed generally adjacent said formation perforating means and operable to define said bleed orifice means; h. said orifice plug means being operable to provide a metering flow path for directing high pressure fluid from a well zone exterior of said tool to said low pressure side of said web means in response to detonation of said formation perforating means whereby a pressure differential applied across said web means may be equalized and release said web means from sealing cooperation with said perforation site; i. said orifice plug means comprises a mounting stud carried by said body means and an insert member carried by said mounting stud; j. said insert member being formed with an orifice operable to define said bleed orifice means and extending from a first end thereon partially toward the second end thereof; k. said insert member being formed with a necked down portion adjacent the second end of said orifice whereby said insert may be sheared at said necked down portion by explosive energy acting on the second end of said insert member such that said orifice thereafter extends entirely through the remaining portion of said insert.
 11. An apparatus according to claim 10 wherein the second end of said insert member comprises a material which is dissolvable in salt water.
 12. In a method of effecting well formation perforating and sealing with a tool comprising, a. body means; b. web means mounted on said body means, said web means including outer lip means; c. said web means being operable to move into sealing cooperation with a perforation site, defined within a formation surrounding a well bore; and d. a formation perforating means carried by said body means and disposed adjacent said web means; e. said formation perforating means having means for directing explosive energy into said formation surrounding said well bore to form a perforation in said formation and to establish a flow path between fluid within said formation and an interior portion of said body means; the improvement comprising: providing bleed orifice means operable to communicate with said web means and operable to meter fluid from a high pressure side to a low pressure side of said web mean; causing a pressure differential operating across said bleed orifice means to be equalized after a predetermined period of time, which period of time is a function of the cross sectional area of said bleed orifice means and said pressure differential; and maintaining said bleed orifice means operable to extend from said outer lip means of said web means to communicate with said flow path. 